95% of commercial jobs are had through having contacts in the industry. Just start calling around to property mainenance companies or developers and they will point you in the right direction. Most people are friendlier than you would think. I was a little nervous when first getting into a bunch of commercial work, but thats how you really grow a business. Residentials will only get you so far. If you bid on a job and lose it, dont get upset just keep going. We had damn near 400k out in bids last year that we didn't land, but we just keep going and bidding. You get the ones you bid correctly and learn from the ones you dont.
Most commercial work wont allow lowball bids as well, so its nice to know you are competing with legitimate firms out there. Also dont grow too fast, meaning, Dont bid on properties that you are not equiped to handle immediately.